A steering apparatus is an apparatus for applying a steering angle to the front wheels of an automobile based on operation of a steering wheel. FIG. 8 illustrates an example of a conventional steering apparatus that is disclosed in JP2010-36677(A). In this steering apparatus, a steering shaft 2 is supported on the inside of a steering column 1 so as to be able to rotate freely, and a steering wheel 3 is fastened to the rear end section of the steering shaft 2. The steering column 1, by way of a column-side bracket 4, is supported by a vehicle-side bracket 5 that is fastened to the vehicle body. In this example, in order to be able to adjust the up-down position and the forward-backward position of the steering wheel 3, the steering column 1 and steering shaft 2 are constructed so as to be able to expand and contract, and a housing 6 for an electric power-steering apparatus that is connected and fastened to the front end section of the steering column 1 is supported by a lower bracket 7 that is fastened to the vehicle body so as to be able to pivot around a horizontal shaft 8. The middle section of the steering column 1 is supported by the column-side bracket 4 such that the up-down position and forward-backward position can be adjusted.
An electric motor that is the auxiliary power source for an electric power-steering apparatus is supported by the housing 6. This electric power-steering apparatus outputs torque after adding an auxiliary torque that corresponds to the direction and size of torque inputted from the steering shaft 2 from an electric motor 9. This output torque is transmitted to the input shaft of a steering gear unit 12 by way of a universal joint 10a, an intermediate shaft 11, and another universal joint 10b, and pushes or pulls a pair of left and right tie rods 13. As these tie rods 13 are pushed or pulled, knuckles that support the front wheels pivotally displace and apply a steering angle to the front wheels.
When an automobile that is equipped with this kind of steering apparatus is involved in a collision accident, following a primary collision of the automobile colliding into another automobile or the like, a secondary collision occurs when the body of the driver collides with the steering wheel 3. In order to lessen the impact that is applied to the body of the driver due to this secondary collision, preferably, during this secondary collision, the steering wheel 3 will displace in the forward direction while absorbing the impact energy that is applied from the body of the driver. In order to accomplish this, various kinds of construction of shock absorbing steering apparatuses, such as disclosed in JP2010-36677(A), JP2010-13010(A) and JP2010-2011967(A), have been proposed and widely implemented. In this kind of shock absorbing steering apparatus, in order to adequately protect the driver during a secondary collision, it is necessary for the collapse stroke, which is the length that the steering wheel 3 can displace in the forward direction during a secondary collision, to be as long as possible.
On the other hand, in order to prevent an automobile from being stolen, a steering lock apparatus is installed that, when the ignition switch has been turned OFF, restricts the steering shaft from turning by causing a key lock pin that is provided on the steering column side to engage with a key lock collar that is provided on the steering shaft side. In order to construct this steering lock apparatus, it is necessary to provide a key lock cylinder on part of the steering column in order to house the key lock pin so as to be able to displace in the radial direction of the steering column. Taking into consideration operability, preferably this key lock cylinder is provided in the portion near the rear end of the steering column.
In this kind of steering apparatus, in consideration of the support rigidity and support strength with respect to the vehicle body, construction is employed wherein stationary-side support plate sections that are located on the sides of the steering column are provided in a vehicle-side bracket that is supported by and fastens to the vehicle body, and a column-side bracket that supports the steering column is supported by these stationary-side support plate sections so as to be able to break away toward the front due to impact in a secondary collision. However, in this kind of construction, when stationary-side support plate sections are provided on both the left and right sides of the steering column, protruding objects such as the key lock cylinder hit the rear-end edge of one of the stationary-side support plate sections during the initial stage of a secondary collision, and hinders the forward displacement of the steering column beyond that point, so in disadvantageous from the aspect of maintaining the collapse stroke.
In JP2010-13010(A), construction is disclosed that is different from the construction described above of providing stationary-side support plate sections, and in this construction a column-side bracket that supports the middle section of the steering column is suspended from and supported by the bottom side of a flat support plate that is fastened to the vehicle body side so as to be able to displace in the forward direction due to impact during a secondary collision. In the case of this kind of construction, displacement in the forward direction of objects that are provided on the steering column and that protrude to the side such as the key lock cylinder, casing for a combination switch and the like is not prevented by a portion that is fastened to the vehicle body such as a vehicle-side bracket, which is advantageous from the aspect of maintaining the collapse stroke. However, this construction is disadvantageous from the aspect of improving support rigidity of the steering column with respect to the vehicle body.
Moreover, JP2010-201967(A) discloses construction wherein a stationary-side support plate section of the vehicle-side bracket is provided on only one side of the steering column. With this kind of construction, the collapse stroke is not limited by objects provided on the steering column that protrude to the side hitting the stationary-side support plate section. However, in the case of this kind of construction, the steering column is supported by the vehicle-side bracket on only one side in the width direction. Therefore, even though construction is such that a stationary-side support plate section is provided in the vehicle-side bracket, the support rigidity of the steering column is cannot always be made high enough.
JP2005-280655(A) discloses an example of construction for absorbing an impact load during a secondary collision. In this construction, during a secondary collision, by having a sliding shaft displace in the forward direction while pushing and expanding the width of a long hole that is formed in a support member in the forward-backward direction of the vehicle, impact load due to the secondary collision is absorbed. Moreover, there are restricting sections on both sides in the width direction of the support member that prevent the support member from expanding in the width direction, in order that the impact load can be absorbed stably. Furthermore, JP2007-69821(A) and JP2008-100597(A) disclose a steering apparatus in which a friction member having multi-plate construction is located between the vehicle-side bracket and column-side bracket in order to increase the surface area of friction between the surfaces of these brackets that undergo relative displacement during a secondary collision, and increase the holding force for keeping the steering wheel in the adjusted position.
All of the related technical literature described above is incorporated into this specification by reference.